To the Editor: The discussion of fibrinolysis in the recently published guidelines for the management of acute coronary syndromes 20061 is interesting. The recommendations clearly indicate that second-generation agents should be preferred to streptokinase in all circumstances. The guidelines reference the GUSTO-I trial data2 as the primary support for those recommendations. These data are, at best, debatable in terms of showing any benefit of front-loaded tissue plasminogen activator over streptokinase, and then only in limited circumstances (ie, patients aged less than 75 years with anterior infarcts and within 4 hours of the onset of symptoms).3,4

To my knowledge, there have been no head-to-head trials of this size of the other fibrinolytic agents discussed against streptokinase. Thus there is no justification for the blanket superiority that is accredited to these agents, both by implication and explicitly, in the guidelines.

It is a matter of some concern that guidelines from such respected groups should make statements that will be used broadly by clinicians, but that go beyond the evidence base to which they refer.

On the balance of information available there is no compelling case to relegate streptokinase from the front line.

In reply: As Bezzina states, the GUSTO-I trial is the main source of evidence for the superiority of front-loaded alteplase (rt-PA) over streptokinase, showing a 1% absolute and 15% relative benefit.1 Subgroup analysis suggested that only certain groups benefited, but this is an inappropriate use of subgroups, and the result should be applied overall. A clear mechanistic reason for the advantage of rt-PA — greater 90-minute full coronary patency — has also been demonstrated.2

Meta-analyses of the percutaneous coronary intervention (PCI) trials in acute myocardial infarction have all shown benefit over fibrinolysis. However, the benefit of PCI is greater compared with streptokinase than with plasminogen activators.3 Although not providing a head-to-head comparison, these data also support the superiority of plasminogen activators over streptokinase.

The second generation plasminogen activator studies have all compared these with the “gold standard” front-loaded rt-PA. These agents have been shown to not be inferior in relation to mortality,4,5 and tenecteplase showed a decrease in systemic bleeding.5 Administration as a bolus without the adverse reactions commonly seen with streptokinase (such as hypotension) make them much more convenient and safe, particularly in smaller institutions.

In addition, streptokinase is an inappropriate choice in Indigenous patients because many have high levels of anti-streptokinase IgG and streptokinase resistance.6